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Myostatin

  1. #1
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    Myostatin
    posted by biggerstronger at cuttingedgemuscle


    Regulation of Myostatin in Vivo by Growth and Differentiation Factor-Associated Serum Protein-1: A Novel Protein with Protease Inhibitor and Follistatin Domains
    Jennifer J. Hill, Yongchang Qiu, Rodney M. Hewick and Neil M. Wolfman
    Department of Protein Chemistry and Proteomics (J.J.H., Y.Q., R.M.H.), and Department of Musculoskeletal Sciences (N.M.W.), Wyeth Research, Cambridge, Massachusetts 02140

    Address all correspondence and requests for reprints to: Jennifer J. Hill, Department of Protein Chemistry and Proteomics, Wyeth Research, 200 Cambridge Park Drive, Cambridge, Massachusetts 02140. E-mail: jhill@wyeth.com.

    Myostatin, a member of the TGFß superfamily, is a potent and specific negative regulator of skeletal muscle mass. In serum, myostatin circulates as part of a latent complex containing myostatin propeptide and/or follistatin-related gene (FLRG). Here, we report the identification of an additional protein associated with endogenous myostatin in normal mouse and human serum, discovered by affinity purification and mass spectrometry. This protein, which we have named growth and differentiation factor-associated serum protein-1 (GASP-1), contains multiple domains associated with protease-inhibitory proteins, including a whey acidic protein domain, a Kazal domain, two Kunitz domains, and a netrin domain. GASP-1 also contains a domain homologous to the 10-cysteine repeat found in follistatin, a protein that binds and inhibits activin, another member of the TGFß superfamily. We have cloned mouse GASP-1 and shown that it inhibits the biological activity of mature myostatin, but not activin, in a luciferase reporter gene assay. Surprisingly, recombinant GASP-1 binds directly not only to mature myostatin, but also to the myostatin propeptide. Thus, GASP-1 represents a novel class of inhibitory TGFß binding proteins.


    Differential Response to Exogenous and Endogenous Myostatin in Myoblasts Suggests that Myostatin Acts as an Autocrine Factor in Vivo
    Ramón Ríos1, Susana Fernández-Nocelos, Isabel Carneiro, Víctor M. Arce and Jesús Devesa
    Departamento de Fisioloxía, Facultade de Medicina, Universidade de Santiago de Compostela, A Coruña 15782, Spain

    Address all correspondence and requests for reprints to: Víctor M. Arce, M.D., Ph.D., Departamento de Fisioloxía, Facultade de Medicina, Universidade de Santiago de Compostela, San Francisco 1, 15782 Santiago de Compostela, Spain. E-mail: fsvarce@usc.es.

    Myostatin is a member of the TGF-ß superfamily that is essential for proper regulation of skeletal muscle growth. As do other TGF-ß superfamily members, myostatin signals into the cell via a receptor complex that consists of two distinct transmembrane proteins, known as the type I and type II receptors. Vertebrates have seven distinct type I receptors, each of which can mix and match with one of five type I receptors to mediate signals for all the TGF-ß family ligands. Accumulating evidence indicates that myostatin shares its pair of receptors with activin, and therefore, the question arises about how specificity in signaling is achieved. Our hypothesis is that a mechanism has to exist to restrict myostatin actions to the muscle cells. To investigate this possibility, we compared the effect of endogenous myostatin (myostatin overexpressed by myoblasts) and exogenous myostatin (recombinant myostatin added to the culture medium) in cultured myoblasts. As opposed to exogenous myostatin, endogenous myostatin induced the transcription of a reporter vector in cultured myoblasts. Notably, the myostatin concentrations that failed to induce a response in myoblasts were effective in MCF-7 cells (human mammary carcinoma) and in HepG2 cells (human hepatic carcinoma). Based on our observations, we propose that a mechanism exists that differentially regulates the bioavailability of endogenous and exogenous myostatin to muscle cells. This is consistent with a model in which myostatin actions are exerted in vivo in an autocrine fashion

    Activation of latent myostatin by the BMP-1/tolloid family of metalloproteinases
    Neil M. Wolfman * , Alexandra C. McPherron , William N. Pappano ¶, Monique V. Davies ||, Kening Song **, Kathleen N. Tomkinson *, Jill F. Wright *, Liz Zhao **, Suzanne M. Sebald , Daniel S. Greenspan ¶ and Se-Jin Lee

    *Department of Inflammation, ||Antibody Technology Group, and **Department of Cardiovascular and ********* Diseases, Wyeth Research, 200 CambridgePark Drive, Cambridge, MA 02140; Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205; and Departments of ¶Biomolecular Chemistry and Pathology and Laboratory Medicine, University of Wisconsin Medical School, 1300 University Avenue, Madison, WI 53706

    Edited by Eric N. Olson, University of Texas Southwestern Medical Center, Dallas, TX and approved October 6, 2003 (received for review August 4, 2003)


    Myostatin is a transforming growth factor family member that acts as a negative regulator of skeletal muscle growth. Myostatin circulates in the blood of adult mice in a noncovalently held complex with other proteins, including its propeptide, which maintain the C-terminal dimer in a latent, inactive state. This latent form of myostatin can be activated in vitro by treatment with acid; however, the mechanisms by which latent myostatin is activated in vivo are unknown. Here, we show that members of the bone morphogenetic protein-1/tolloid (BMP-1/TLD) family of metalloproteinases can cleave the myostatin propeptide in this complex and can thereby activate latent myostatin. Furthermore, we show that a mutant form of the propeptide resistant to cleavage by BMP-1/TLD proteinases can cause significant increases in muscle mass when injected into adult mice. These findings raise the possibility that members of the BMP-1/TLD family may be involved in activating latent myostatin in vivo and that molecules capable of inhibiting these proteinases may be effective agents for increasing muscle mass for both human therapeutic and agricultural applications.

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    Rudy '08 Golgo13's Avatar
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    So how long till we start seeing ads from MuscleTech telling us they have something to block it?

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    The thing is, there are only a few really good ways to block it specifically, and both are pretty unrealistic for our purposes. Even if GASP-1 were available (and it is), using it is no guarantee that it doesn't allso inhibit the other members of the TGFb family, which would be detrimental

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    Originally posted by einstein1905
    The thing is, there are only a few really good ways to block it specifically, and both are pretty unrealistic for our purposes. Even if GASP-1 were available (and it is), using it is no guarantee that it doesn't allso inhibit the other members of the TGFb family, which would be detrimental

    Valid point, also the effects in mice may not tranlate to man.

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    Junior Bodybuilder majic's Avatar
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    There was an article about Gene Doping in Scientific American July issue. They talked about the myostatin gene, so it sparked my interest when I saw it (because I've been following the research and studies on the myostatin gene). They had a bull in there that was freaking jacked. It was a bull that was born without the myostatin gene, but it was done through selective breeding. It was a belgian blue, if anyone is interested in looking up pictures.

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    some belgian blue pics, just to give you an idea of how muscled these myostatin lacking bulls are:






    and here's an angus bull, just for comparison:


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    but then again, those mutherfuckers are probably making 50+ mg of test per day, whereas a normal human only makes 2.5-11 mg of test per day, naturally.

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    Good pics, the muscles on the myostain lacking bulld look all fucked up though and disproportionate.

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    Yeah -- but then again, bull physiology is different than that of humans, who is to say that it's disproportionate, I personally wouldn't know because I'm no bull judge heh. But it does bring to mind images of comic books from when I was a kid... overgrown super-villains with bulging arms, and 10-pack stomach muscles... muscles growing muscles, popping with veins, and so over-bulked that the muscles are distorted from the lack of skeletal real estate.

    Sabertooth, and venom, and the beast.

    Random side note: I always wanted to be the beast, when I watched x-men on Saturday mornings. He had the perfect balance between being inhumanly large, and superhuman intelligence. He could also hang from ceilings. But someone could have loaned the bro a razor... you gotta have the blue hair.

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